Chemistry – Acids, bases and salts - Oxides | e-Consult
Acids, bases and salts - Oxides (1 questions)
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Amphoteric oxides exhibit properties of both acids and bases. This is because the metal cation in the oxide can accept a proton (acting as an acid) and the oxide ion can accept a proton (acting as a base). For example, \$Al2O3\$ reacts with a strong acid (e.g., HCl) to form an aluminium salt and water, demonstrating acidic properties:
| \$Al2O3(s) + 6HCl(aq) \rightarrow 2AlCl3(aq) + 3H2O(l)\$ |
And it reacts with a strong base (e.g., NaOH) to form an aluminium hydroxide and water, demonstrating basic properties:
| \$Al2O3(s) + 2NaOH(aq) + 3H2O(l) \rightarrow 2Na[Al(OH)4](aq) \$ |
Similarly, \$ZnO\$ reacts with acids and bases. The zinc cation can accept a proton, and the oxide ion can donate a proton. These dual reactions are characteristic of amphoteric oxides.